111,767 research outputs found
Unified chiral analysis of the vector meson spectrum from lattice QCD
The chiral extrapolation of the vector meson mass calculated in
partially-quenched lattice simulations is investigated. The leading one-loop
corrections to the vector meson mass are derived for partially-quenched QCD. A
large sample of lattice results from the CP-PACS Collaboration is analysed,
with explicit corrections for finite lattice spacing artifacts. To incorporate
the effect of the opening decay channel as the chiral limit is approached, the
extrapolation is studied using a necessary phenomenological extension of chiral
effective field theory. This chiral analysis also provides a quantitative
estimate of the leading finite volume corrections. It is found that the
discretisation, finite-volume and partial quenching effects can all be very
well described in this framework, producing an extrapolated value of M_\rho in
excellent agreement with experiment. This procedure is also compared with
extrapolations based on polynomial forms, where the results are much less
enlightening.Comment: 30 pages, 13 fig
Multi-cell battery protection system
A multi-cell battery protection system is described wherein each cell has its own individual protective circuit. The protective circuits consist of a solid state comparator unit and a high current switching device such as a relay. The comparator units each continuously monitor the associated cell and when the cell voltage either exceeds a predetermined high level or falls below a predetermined low level, the relay is actuated whereby a bypass circuit is completed across the cell thereby effectively removing the cell from the series of cells
Finite subgroups of simple algebraic groups with irreducible centralizers
We determine all finite subgroups of simple algebraic groups that have
irreducible centralizers - that is, centralizers whose connected component does
not lie in a parabolic subgroup.Comment: 24 page
Interplay of Spin and Orbital Angular Momentum in the Proton
We derive the consequences of the Myhrer-Thomas explanation of the proton
spin problem for the distribution of orbital angular momentum on the valence
and sea quarks. After QCD evolution these results are found to be in very good
agreement with both recent lattice QCD calculations and the experimental
constraints from Hermes and JLab
Expanded operational capabilities of the Langley Mach 7 Scramjet test facility
An experimental research program conducted to expand the operational capabilities of the NASA Langley Mach 7 Scramjet Test Facility is described. Previous scramjet testing in this facility was limited to a single simulated flight condition of Mach 6.9 at an altitude of 115,300 ft. The arc heater research demonstrates the potential of the facility for scramjet testing at simulated flight conditions from Mach 4 (at altitudes from 77,000 to 114,000 ft) to Mach 7 (at latitudes from 108,000 to 149,000 ft). Arc heater electrical characteristics, operational problems, measurements of nitrogen oxide contaminants, and total-temperature profiles are discussed
The First Moments of Nucleon Generalized Parton Distributions
We extrapolate the first moments of the generalized parton distributions
using heavy baryon chiral perturbation theory. The calculation is based on the
one loop level with the finite range regularization. The description of the
lattice data is satisfactory and the extrapolated moments at physical pion mass
are consistent with the results obtained with dimensional regularization,
although the extrapolation in the momentum transfer to does show
sensitivity to form factor effects which lie outside the realm of chiral
perturbation theory. We discuss the significance of the results in the light of
modern experiments as well as QCD inspired models.Comment: 14 pages, 9 figure
Physical Nucleon Properties from Lattice QCD
We demonstrate that the extremely accurate lattice QCD data for the mass of
the nucleon recently obtained by CP-PACS, combined with modern chiral
extrapolation techniques, leads to a value for the mass of the physical nucleon
which has a systematic error of less than one percent.Comment: 4 pages, 2 figure
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